Effects Of Organophosphorus And Pyrethroid Pesticides On Estrogen

Part One Research on the estrogenicity of Organophosphorus and pyrethroid pesticidesObjective:To evaluate the estrogenic activities of five Organophosphorus pesticides [phoxim (Pho),malathion (Mai),dimethoate (Dim),monocrotophos (Mon),optunal (Opt)] and four pyrethroid pesticides [fenvalerate (Fen),deltamethrin (Del),cypermethrin (Cyp) and permethrin (Per)].Methods:1. Rat uteri estrogen receptor (ER) competitive binding assay;2. Human breast cancer MCF-7 cell and MDA-MA-435S cell proliferation assay;3. Human breast cancer MCF-7 cell pS2 mRNA expression assay.Results:1. The five organophosphorus pesticides failed to inhibit the binding of 3H-E2 to rat uteri ER while the four pyrethroid pesticicdes were able to bind to the ER through competing against 3H-E2 in vitro,the binding potentials were Fen>Cyp>Per>Del,of which IC50 of Fen and Cyp inhibiting 3H-E2 from binding to ER were 0.479mM and 0.562mM respectively.2. All the pyrethroid pesticides could induce MCF-7 cell proliferation to some extent while the organophosphorus pesticides did not. The estrogenic potencies were ranked as Per>Fen>Cyp>Del. The proliferation induced by Cyp,Per and Del was blocked by ICI 182.780 while Fen was partly inhibited.3. Of the four pyrethroid pesticides tested,only Fen could stimulate the proliferation of MDA-MA-435S cell.4. Fen,Per and Cyp induced pS2 mRNA expression with various potencies while there was no significant effect in Del treated group.Conclusion:1 . Pyrethroid pesticides tested produce an ER-specific,agonist response.2. Fenvalerate induces MCF-7 cell proliferation by a mechanism not involving in ER-mediated pathway.3. Organophosphorus pesticides tested do not show estrogenic potential.